From Cppreference
| Defined in header <istream>
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template<
class CharT,
class Traits = std::char_traits<CharT>
> class basic_istream;
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The class template basic_istream provides support for input operations on streams. It directly inherits basic_ios class and therefore indirectly inherits members of ios_base class.
Two specializations for common character types are defined:
| Defined in header <istream>
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| Type
| Definition
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| istream
| basic_istream<char>
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| wistream
| basic_istream<wchar_t>
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Several objects are defined in <iostream> header to provide access to the standard input (stdin) stream:
extern istream cin; //stdin
extern istream wcin; //stdin (wide character)
Member types
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| Member type
| Definition
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| char_type
| CharT
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| traits_type
| Traits
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| int_type
| Traits::int_type
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| pos_type
| Traits::pos_type
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| off_type
| Traits::off_type
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Member functions
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| constructs the object
(public member function)
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| destructs the object
(public member function)
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Formatted input
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| extracts formatted data
(public member function)
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Unformatted input
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| extracts characters
(public member function)
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| reads the next character without extracting it
(public member function)
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| unextracts a character
(public member function)
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| puts character into input stream
(public member function)
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| extracts characters until the given character is found
(public member function)
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| extracts and discards characters until the given character is found
(public member function)
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| extracts blocks of characters
(public member function)
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| extracts already available blocks of characters
(public member function)
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| returns number of characters extracted by last unformatted input operation
(public member function)
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Positioning
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| returns the input position indicator
(public member function)
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| sets the input position indicator
(public member function)
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Miscellaneous
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| synchronizes with the underlying storage device
(public member function)
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Member classes
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| implements basic logic for preparation of the stream for input operations
(public member class)
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Member types
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| Member type
| Definition
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| char_type
| CharT
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| traits_type
| Traits
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| int_type
| Traits::int_type
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| pos_type
| Traits::pos_type
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| off_type
| Traits::off_type
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State functions
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| checks if no error has occurred i.e. I/O operations are available
(public member function)
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| checks if end-of-file has been reached
(public member function)
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| checks if a recoverable error has occurred
(public member function)
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| checks if a non-recoverable error has occurred
(public member function)
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| checks if an error has occurred (synonym of fail())
(public member function)
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| checks if no error has occurred (synonym of good())
(public member function)
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| returns state flags
(public member function)
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| sets state flags
(public member function)
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| clears error and eof flags
(public member function)
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Formatting
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| copies formatting information
(public member function)
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| manages the fill character
(public member function)
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Miscellaneous
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| manages exception mask
(public member function)
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| sets the locale
(public member function)
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| manages associated stream buffer
(public member function)
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| manages tied stream
(public member function)
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| narrows characters
(public member function)
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| widens characters
(public member function)
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Member functions
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Formatting
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| manages format flags
(public member function)
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| sets specific format flag
(public member function)
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| clears specific format flag
(public member function)
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| manages decimal precision of floating point operations
(public member function)
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| manages field width
(public member function)
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Locales
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| sets locale
(public member function)
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| returns current locale
(public member function)
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Internal extensible array
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| returns an unique index to be used to access elements in the internal extensible array
(public static member function)
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| accesses specified element in the internal extensible array of long elements
(public member function)
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| accesses specified element in the internal extensible array of void* elements
(public member function)
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Miscellaneous
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| registers event callback function
(public member function)
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| sets whether C++ and C IO libraries are interoperable
(public static member function)
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Member classes
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| stream exception
(public member class)
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| initializes standard stream objects
(public member class)
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Member types and constants
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| Type
| Explanation
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| stream open mode type
The following constants are also defined:
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| Constant
| Explanation
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| app
| seek to the end of stream before each write
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| binary
| open in binary mode
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| in
| open for reading
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| out
| open for writing
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| trunc
| discard the contents of the stream when opening
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| ate
| seek to the end of stream immediately after open
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| formatting flags type
The following constants are also defined:
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| Constant
| Explanation
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| dec
| uses decimal base for conversions
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| oct
| use octal base for conversions
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| hex
| use hexadecimal base for conversions
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| basefield
| dec|oct|hex. Useful for masking operations
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| left
| left adjustment (adds fill characters to the right)
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| right
| right adjustment (adds fill characters to the left)
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| internal
| internal adjustment (adds fill characters to the internal designated point)
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| adjustfield
| left|right|internal. Useful for masking operations
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| scientific
| generate floating point types using scientific notation
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| fixed
| generate floating point types using fixed notation
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| floatfield
| scientific|fixed. Useful for masking operations
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| boolalpha
| insert and extract bool type in alphanumeric format
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| showbase
| generate a prefix indicating the numeric base for integer number output
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| showpoint
| generate a decimal-point character unconditionally for floating-point number output
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| showpos
| generate a + character for non-negative numeric output
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| skipws
| skip leading whitespace before certain input operations
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| unitbuf
| flush the output after each output operation
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| uppercase
| replace certain lowercase letters with their uppercase
equivalents in certain output output operations
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| state of the stream type
The following constants are also defined:
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| Constant
| Explanation
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| goodbit
| no error
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| badbit
| irrecoverable stream error
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| failbit
| input/output operation failed (formatting or extraction error)
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| eofbit
| associated input sequence has reached end-of-file
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| seeking direction type
The following constants are also defined:
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| Constant
| Explanation
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| beg
| the beginning of a stream
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| end
| the ending of a stream
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| cur
| the current position of stream position indicator
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| specifies event type
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| callback function type
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